What is luminous flux and what is the practical value of this parameter?

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What is luminous flux and what is the practical value of this parameter?
What is luminous flux and what is the practical value of this parameter?
Anonim

When choosing lighting lamps, we, as a rule, first of all pay attention to such a characteristic as power. In this case, other parameters, in particular the luminous flux, are ignored. Often this happens due to elementary ignorance. After all, we all know very well what kind of light a 60 or 100 W electric lamp will give us, but most of us have a rather vague idea about how good fluorescent or LED lamps are.

luminous flux of an incandescent lamp
luminous flux of an incandescent lamp

Again, the more power the light source has, the greater the energy consumption. And today's prices for utilities are such that, willy-nilly, you have to save. It's time to remember the forgotten school knowledge of physics and find out what the brightness of the light of the lamps actually depends on.

Luminous flux is a key parameter of a light source

In the field of lighting technology, the main receiver of radiation is the human eye. And such a parameter as the luminous flux was just introduced in order to evaluate the effectiveness of the impact of visible rays on it. In other words, this is the power of ray energy. The luminous flux is usually measured in lumens, and the abbreviation for this unit is an abbreviation - lm. The higher it is, the brighter the object that emits it seems to us. If the light flux is emitted by an isotropic point source with a light intensity of one candela, into a solid angle, with a size of 1 steradian, then its power is one lumen.

luminous flux of LED lamps
luminous flux of LED lamps

There is another definition that is more understandable to the common man. According to him, one lumen has such a luminous flux that is emitted by a completely black body at the solidification temperature of pure platinum (1773 ° C) with an area of 0.5305 mm2 "Wait," some will say, - but what about the individual characteristics of people? Some eyes see better, others worse. How in this case to determine, for example, how many lumens is the luminous flux of an incandescent lamp? " This issue was resolved by introducing coefficients for each visible wavelength range and using the curve of the average spectral sensitivity of the eye, the data for which are contained in the corresponding look-up table.

Comparison examples

light flow
light flow

It is curious that there is no clear stable relationship between what electrical energy is absorbed by the lamp, and what kind of light it emits. This characteristic is called "light output", and it is measured in lm / W. If we take, for example, a traditional 100 W incandescent lamp, then its luminous flux is 810 Lm. A 15-watt fluorescent device shines with the same brightness. Their light output, respectively, will be equal to 8, 10 lm / W and 54 lm / W. A typical 40W light bulb puts out approximately 350 lm (light output 8.75 lm/W). Of greatest interest from the point of view of efficiency is the luminous flux of LED lamps. So, the same 810 lm with their help can be obtained by spending only 10 W of energy. This means that they are ten times more efficient than traditional incandescent lamps and one and a half times more efficient than energy-saving fluorescent lamps. We hope that when choosing home light sources, this information will be useful to you, and electricity for lighting in your home will be spent much more efficiently.

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